The present invention relates to intelligence transmission and reception apparatus and more particularly to a novel apparatus incorporating a transmitting and a receiving station utilizing pulse code modulation (PCM) for generating, converting and transmitting intelligence signals.
It is known in the art that transmission systems utilizing pulse code modulation (PCM) possess an advantage, relative to signals transmitted with analogue modulation, in that the signal-to-noise ratio at the receiving equipment is dependent only upon the quantization noise and not upon noise introduced into the transmission network.
With known transmission systems, the analogue signal to be transmitted is sampled to obtain a sequence of amplitude values and the individual amplitude values are then converted into suitable pulse code words or messages to be transmitted to the receiver. According to known sampling theory, the frequency of the individual scanning samples should be at least twice as great as the maximum frequency of the analogue signal to be transmitted. These conditions have frequently been found to be quite disturbing for reasons associated with transmission technology, since neither the pulse frequencies resulting from the required scanning frequency nor the number of information bits per scanning pulse, should exceed a certain value.